Many internal combustion engines include turbochargers, or superchargers configured to force more air mass into an engine's intake manifold and combustion chamber by compressing intake air with a compressor driven by a turbine disposed to capture energy from the flow of the engine exhaust gas. However, the compression of the intake air tends to heat it which tends to reduce the density of this charge air. It is known to use a charge air cooler to compensate for heating caused by supercharging. Charge air coolers may be used with gasoline engines and with diesel engines.
During operation in humid and cooler climates, the size of the CAC may be such that water vapor in the air will condense out and be stored in the CAC. When the air demand of the engine reaches a high enough velocity it can strip the condensed water out of the CAC and ingest it into the engine. However, if too much water is ingested into the engine too rapidly the engine may misfire. Sometimes the misfiring can be extreme.
Efforts have been made to reduce condensation in a charge air cooler. For example, U.S. Pat. No. 7,886,724 to Tai, et al. discloses a charge air cooler arrangement with a cooler bypass. The arrangement causes inlet air to flow through a first charge air cooler downstream from a second cooler and a bypass line arranged for bypassing the second cooler. The temperature of the inlet air is adjusted downstream from the first charge air cooler by adjusting an amount of inlet air flow through the second cooler and the bypass line.
The inventors herein have recognized a number of problems with this approach. One example problem is that when inlet air flows through the bypass line the first charge air cooler does not cool the air to temperatures as low as would otherwise be desirable. Another problem with this approach is that it requires using two charge air coolers thereby increasing material, production, packaging and other costs.
The inventors herein have recognized that under various pressure conditions charge air condensate can be stripped from the cooling tubes of the charge air cooler before excess condensation can build up if the charge air flow rate remains above a certain minimum. For example, at 1 bar atmosphere, a minimum air velocity of 13 m/s at various engine speeds may tend to remove water continuously and prevent excess condensation. And the rate of water stripping will increase with higher charge air flow rates. However, at slow engine speeds the charge air flow rate through the cooling tubes may be too slow to prevent excess condensation buildup. Accordingly, embodiments in accordance with the present disclosure may be configured to ensure that the flow rate in each individual cooling tube, where condensation may occur, may be a kept above a predetermined minimum.
Embodiments may provide a system to control condensation within a plurality of cooling tubes of a charge air cooler for use with an engine. The system may includes an air flow control arrangement configured to selectively ensure a flow rate of charge air through each individual cooling tube is either essentially zero or above a predetermined minimum flow rate in accordance with predetermined operating conditions of the engine. In this way excess condensation may be avoided, and condensation that may be present may be continually stripped from individual cooling tubes such that excess condensation will not be passed to the combustion chamber of the engine. In this way engine misfire due to excessive water ingestion may be avoided.
Embodiments may also provide a charge air cooler for use with an engine. The charge air cooler may include a plurality of regulate-able cooling tubes configured to receive a charge air from a respective first side of each cooling tube and to output the charge air from a respective second side of each cooling tube. The charge air cooler may also include a flow regulating arrangement configured to pass the charge air through the plurality of regulate-able cooling tubes in a selective way to provide either no flow through a particular tube, or flow at a flow rate above a preselected minimum flow rate. The charge air cooler may also include one or more additional cooling tubes configured receive cooling air when the engine is operable. The regulate-able cooling tubes and the additional cooling tubes may all be included in the same charge air cooler.
Embodiments may also provide a method of controlling condensation accumulation within cooling tubes included in a single charge air cooler. The charge air cooler may be configured for providing cooled charge air to an engine. The method may include controlling passage of the charge air through each of the cooling tubes in order to keep a flow rate in each individual cooling tube to either above a predetermined minimum flow rate, or at substantially no flow in accordance with operating conditions of the engine.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.